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Python | Flatten a 2d numpy array into 1d array

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  • Difficulty Level : Basic
  • Last Updated : 15 Mar, 2019
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Given a 2d numpy array, the task is to flatten a 2d numpy array into a 1d array. Below are a few methods to solve the task.

Method #1 : Using np.flatten()




# Python code to demonstrate
# flattening a 2d numpy array
# into 1d array
  
import numpy as np
  
ini_array1 = np.array([[1, 2, 3], [2, 4, 5], [1, 2, 3]])
  
# printing initial arrays
print("initial array", str(ini_array1))
  
# Multiplying arrays
result = ini_array1.flatten()
  
# printing result
print("New resulting array: ", result)

Output:

initial array [[1 2 3]
 [2 4 5]
 [1 2 3]]
New resulting array:  [1 2 3 2 4 5 1 2 3]

 
Method #2: Using np.ravel()




# Python code to demonstrate
# flattening a 2d numpy array
# into 1d array
  
import numpy as np
  
ini_array1 = np.array([[1, 2, 3], [2, 4, 5], [1, 2, 3]])
  
# printing initial arrays
print("initial array", str(ini_array1))
  
# Multiplying arrays
result = ini_array1.ravel()
  
# printing result
print("New resulting array: ", result)

Output:

initial array [[1 2 3]
 [2 4 5]
 [1 2 3]]
New resulting array:  [1 2 3 2 4 5 1 2 3]

 
Method #3: Using np.reshape()




# Python code to demonstrate
# flattening a 2d numpy array
# into 1d array
  
import numpy as np
  
ini_array1 = np.array([[1, 2, 3], [2, 4, 5], [1, 2, 3]])
  
# printing initial arrays
print("initial array", str(ini_array1))
  
# Multiplying arrays
result = ini_array1.reshape([1, 9])
  
# printing result
print("New resulting array: ", result)

Output:

initial array [[1 2 3]
 [2 4 5]
 [1 2 3]]
New resulting array:  [[1 2 3 2 4 5 1 2 3]]

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